1. Field of the Invention
The present invention relates to a developing device in the field of electrophotographic image forming apparatuses.
2. Description of the Prior Art
A developing device accommodating a toner therein is mounted detachably to an electrophotographic image forming apparatus. Images are formed by setting a developing roll provided at the developing device in opposition to a photosensitive drum, feeding the toner accommodated in a toner tank to the developing roll while agitating and conveying the toner by an agitator, and making an electrostatic latent image formed on the photosensitive drum visible by the toner.
If left to stand for a while, the toner accommodated in the toner tank coagulates. Therefore, the initial resistance at the time the toner is scraped off from the mass of toner, which has coagulated in the toner tank, and is agitated by the agitator is large.
Here, in order to minimize the resistance at the initial stages of agitation of the toner, there are proposed structures such as using an elastic member for the agitator (Japanese Patent Applications Laid-Open (JP-A) Nos. 3-149579, 4-191768), and changing by 180 degrees the projecting direction of the agitator mounted on a rotating shaft, at a central portion and the both end portions of the rotating shaft (JP-A-4-204466).
However, in either of these developing devices, the rotating shaft must have a strength sufficient to endure the resistance when the coagulated toner is scraped off. Consequently, the rotating shaft must be provided with a strength greater than or equal to the strength necessary for agitating and feeding the toner at the time of normal operation. Thus, the device becomes large and the manufacturing cost thereof rises.